Journal articles: 'XAS spectroscopy'

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Sarangi, Ritimukta. "A biological perspective towards a standard for information exchange and reporting in XAS." Journal of Synchrotron Radiation 25, no. 4 (June 27, 2018): 944–52. http://dx.doi.org/10.1107/s1600577518008779.

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The complex structural landscape of biological samples and their sensitivity to X-ray exposure leads to specific challenges in biological X-ray absorption spectroscopy (bio-XAS) research, which in turn has necessitated standardization of various aspects of bio-XAS data measurement, analysis and interpretation. The bio-XAS community is therefore well suited for the development of a data-reporting standard with the specific aim of creating a feedback loop for improving/standardizing data analysis protocols and optionally to make published data available to collaborators/researchers in a meaningful and quantitative format. The XIF (XAFS information file) reporting format presented here contains key experimental and analysis parameters, useful in developing a consistent platform for bio-XAS research worldwide. Such a reporting standard, enforced by the user community and publishing groups alike, can be an important step towards the standardization of data measurement and analysis techniques in bio-XAS.

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Fracchia, Martina, Paolo Ghigna, Alberto Vertova, Sandra Rondinini, and Alessandro Minguzzi. "Time-Resolved X-ray Absorption Spectroscopy in (Photo)Electrochemistry." Surfaces 1, no. 1 (December 5, 2018): 138–50. http://dx.doi.org/10.3390/surfaces1010011.

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This minireview aims at providing a complete survey concerning the use of X-ray absorption spectroscopy (XAS) for time-resolved studies of electrochemical and photoelectrochemical phenomena. We will see that time resolution can range from the femto-picosecond to the second (or more) scale and that this joins the valuable throughput typical of XAS, which allows for determining the oxidation state of the investigated element, together with its local structure. We will analyze four different techniques that use different approaches to exploit the in real time capabilities of XAS. These are quick-XAS, energy dispersive XAS, pump & probe XAS and fixed-energy X-ray absorption voltammetry. In the conclusions, we will analyze possible future perspectives for these techniques.

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Chantler, Christopher T., M. Tauhidul Islam, Stephen P. Best, Lachlan J. Tantau, Chanh Q. Tran, Mun Hon Cheah, and Andrew T. Payne. "High-accuracy X-ray absorption spectra from mMsolutions of nickel (II) complexes with multiple solutions using transmission XAS." Journal of Synchrotron Radiation 22, no. 4 (June 19, 2015): 1008–21. http://dx.doi.org/10.1107/s1600577515006190.

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A new approach is introduced for determining X-ray absorption spectroscopy (XAS) spectra on absolute and relative scales using multiple solutions with different concentrations by the characterization and correction of experimental systematics. This hybrid technique is a development of standard X-ray absorption fine structure (XAFS) along the lines of the high-accuracy X-ray extended range technique (XERT) but with applicability to solutions, dilute systems and cold cell environments. This methodology has been applied to determining absolute XAS of bis(N-n-propyl-salicylaldiminato) nickel(II) and bis(N-i-propyl-salicylaldiminato) nickel(II) complexes with square planar and tetrahedral structures in 15 mMand 1.5 mMdilute solutions. It is demonstrated that transmission XAS from dilute systems can provide excellent X-ray absorption near-edge structure (XANES) and XAFS spectra, and that transmission measurements can provide accurate measurement of subtle differences including coordination geometries. For the first time, (transmission) XAS of the isomers have been determined from low-concentration solutions on an absolute scale with a 1–5% accuracy, and with relative precision of 0.1% to 0.2% in the active XANES and XAFS regions after inclusion of systematic corrections.

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Tamenori, Yusuke. "Electron yield soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions." Journal of Synchrotron Radiation 20, no. 3 (March 16, 2013): 419–25. http://dx.doi.org/10.1107/s0909049513003592.

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Ambient-pressure soft X-ray photoabsorption spectroscopy (XAS) was demonstrated to be applicable to the chemical analysis of hydrated transition-metal compounds. For this purpose, even under ambient-pressure conditions, electron yield detection XAS (EY-XAS), based on a simple drain-current set-up, was used to overcome a weakness in fluorescence yield detection XAS (FY-XAS), which does not give a pure soft XAS. The feasibility of EY-XAS was investigated and it was clarified that the EY-XAS under ambient-pressure conditions corresponds to the mixed data of the total EY and conversion EY spectra. Normal ambient-pressure EY-XAS analysis was applied to anhydrous (CoCl2) and to hydrated (CoCl2·6H2O) cobalt chloride at the CoL23-edge. The present measurements demonstrated the ability to unambiguously distinguish the different chemical states of cobalt ions, relying upon spectral differences that indicate octahedral/quasi-octahedral structural changes as a result of hydration/dehydration reactions.

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Martini, Andrea, and Elisa Borfecchia. "Spectral Decomposition of X-ray Absorption Spectroscopy Datasets: Methods and Applications." Crystals 10, no. 8 (August 1, 2020): 664. http://dx.doi.org/10.3390/cryst10080664.

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X-ray absorption spectroscopy (XAS) today represents a widespread and powerful technique, able to monitor complex systems under in situ and operando conditions, while external variables, such us sampling time, sample temperature or even beam position over the analysed sample, are varied. X-ray absorption spectroscopy is an element-selective but bulk-averaging technique. Each measured XAS spectrum can be seen as an average signal arising from all the absorber-containing species/configurations present in the sample under study. The acquired XAS data are thus represented by a spectroscopic mixture composed of superimposed spectral profiles associated to well-defined components, characterised by concentration values evolving in the course of the experiment. The decomposition of an experimental XAS dataset in a set of pure spectral and concentration values is a typical example of an inverse problem and it goes, usually, under the name of multivariate curve resolution (MCR). In the present work, we present an overview on the major techniques developed to realize the MCR decomposition together with a selection of related results, with an emphasis on applications in catalysis. Therein, we will highlight the great potential of these methods which are imposing as an essential tool for quantitative analysis of large XAS datasets as well as the directions for further development in synergy with the continuous instrumental progresses at synchrotron sources.

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Ewels, Philip, Thierry Sikora, Virginie Serin, Chris P. Ewels, and Luc Lajaunie. "A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database: eelsdb.eu." Microscopy and Microanalysis 22, no. 3 (February 22, 2016): 717–24. http://dx.doi.org/10.1017/s1431927616000179.

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AbstractThe electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors’ original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra.

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Uehara, Akihiro, Toshiyuki Fujii, Hajimu Yamana, and Yoshihiro Okamoto. "An in-situ X-ray absorption spectroelectrochemical study of the electroreduction of uranium ions in HCl, HNO3, and Na2CO3 solutions." Radiochimica Acta 104, no. 1 (January 28, 2016): 1–9. http://dx.doi.org/10.1515/ract-2015-2436.

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8

MATSUSHITA, TOMOHIRA, MASAICHIRO MIZUMAKI, NAOSHI IKEDA, MAKOTO NAKAZAWA, AKANE AGUI, YUJI SAITOH, TAKESHI NAKATANI, AKITAKA YOSHIGOE, and SHIN NAKAMURA. "X-RAY ABSORPTION SPECTROSCOPY IN NaCo2O4, LaCoO3andSrCoO3." Surface Review and Letters 09, no. 02 (April 2002): 1327–31. http://dx.doi.org/10.1142/s0218625x02003755.

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We have performed Co 2p X-ray absorption spectroscopy (XAS) on a mixed valence hexagonal layered system NaCo 2 O 4, which shows large thermopower and metallic conductivity. We also measured XAS for SrCoO 3 and LaCoO 3 as examples of typical Co ionic states. The Co ions of the last two materials are octahedrally surrounded by oxygen atoms. A Co atom in NaCo 2 O 4 also has octahedral coordination with oxygen atoms but it is distorted slightly. The Co ions in SrCoO 3 and LaCoO 3 are in the d5 and d6 configuration respectively. The spectrum of NaCo 2 O 4 resembles that of LaCoO 3 rather than that of SrCoO 3; the Co ions in NaCo 2 O 4 can be regarded as the d6 configuration. Also, we have tried to calculate the XAS spectra by using the charge-transfer multiplet model (CT-M). Although we could not find out the best-fitting parameters, the results suggested the itinerancy of the Co 3d states.

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De Santis, Emiliano, Emma Shardlow, Francesco Stellato, Olivier Proux, Giancarlo Rossi, Christopher Exley, and Silvia Morante. "X-Ray Absorption Spectroscopy Measurements of Cu-ProIAPP Complexes at Physiological Concentrations." Condensed Matter 4, no. 1 (January 18, 2019): 13. http://dx.doi.org/10.3390/condmat4010013.

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The amyloidogenic islet amyloid polypeptide (IAPP) and the associated pro-peptide ProIAPP1–48 are involved in cell death in type 2 diabetes mellitus. It has been observed that interactions of this peptide with metal ions have an impact on the cytotoxicity of the peptides as well as on their deposition in the form of amyloid fibrils. In particular, Cu(II) seems to inhibit amyloid fibril formation, thus suggesting that Cu homeostasis imbalance may be involved in the pathogenesis of type 2 diabetes mellitus. We performed X-ray Absorption Spectroscopy (XAS) measurements of Cu(II)-ProIAPP complexes under near-physiological (10 μM), equimolar concentrations of Cu(II) and peptide. Such low concentrations were made accessible to XAS measurements owing to the use of the High Energy Resolved Fluorescence Detection XAS facility recently installed at the ESRF beamline BM16 (FAME-UHD). Our preliminary data show that XAS measurements at micromolar concentrations are feasible and confirm that ProIAPP1–48-Cu(II) binding at near-physiological conditions can be detected.

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Firet, Nienke J., Thomas Burdyny, Nathan T. Nesbitt, Sanjana Chandrashekar, Alessandro Longo, and Wilson A. Smith. "Copper and silver gas diffusion electrodes performing CO2 reduction studied through operando X-ray absorption spectroscopy." Catalysis Science & Technology 10, no. 17 (2020): 5870–85. http://dx.doi.org/10.1039/d0cy01267j.

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11

Engelbrecht, J. A. A., and J. R. Botha. "Infrared Reflectivity Determination of Alloy Composition in AlxGa1–xAs and InxGa1–xAs Structures." Applied Spectroscopy 51, no. 3 (March 1997): 433–37. http://dx.doi.org/10.1366/0003702971940332.

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Fourier transform infrared reflectance spectroscopy can be used to establish the height of the transverse optic mode peak of AlAs at 361 cm−1. The peak height is found to be linearly dependent on the aluminum content in Al xGa1– xAs layers on GaAs substrates. Previously published spectra for In xGa1– xAs yielded a similar result for the In content, from the transverse optic mode peak of InAs at 220 cm−1. A quick and nondestructive technique is proposed for the determination of the aluminum and indium mole fraction in these structures.

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12

Wang, Qian, Xiaomei Wu, Lingcong Chen, Zheng Yang, and Zheng Fang. "Plastic Classification with X-ray Absorption Spectroscopy Based on Back Propagation Neural Network." Applied Spectroscopy 71, no. 11 (September 12, 2017): 2538–48. http://dx.doi.org/10.1177/0003702817706921.

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Currently, spectral analysis methods used in the classification of plastics have limitations that do not apply to opaque plastics or the stability of experimental results is not strong. In this paper, X-ray absorption spectroscopy (XAS) has been applied to classify plastics due to its strong penetrability and stability. Fifteen kinds of plastics are selected as specimens. X-ray, which is excited by a voltage of 60 kV, penetrated these specimens. The spectral data acquired by CdTe X-ray detector are processed by principal component analysis (PCA) and other data analysis methods. Then the back propagation neural networks (BPNN) algorithm is used to classify the processed data. The average recognition rate reached 96.95% and classification results of all types of plastic results were analyzed in detail. It indicates that XAS has the potential to classify plastics and that XAS can be used in some fields such as plastic waste sorting and recycling. At the same time, the technology of XAS, in the future, can also be used to classify more substances.

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13

Ascone, Isabella, Wolfram Meyer-Klaucke, and Loretta Murphy. "Experimental aspects of biological X-ray absorption spectroscopy." Journal of Synchrotron Radiation 10, no. 1 (December 24, 2002): 16–22. http://dx.doi.org/10.1107/s0909049502022598.

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Spectroscopic techniques, like X-ray absorption spectroscopy, will provide important input for integrated biological projects in genomics and proteomics. This contribution summarizes technical requirements and typical set-ups for both simple and complex biological XAS experiments. An overview on different strategies for sample preparation is discussed in detail. Present and future BioXAS spectrometers are presented to help potential users in locating the spectrometer required for their biological application.

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Goode, Angela E., Alexandra E. Porter, Mary P. Ryan, and David W. McComb. "Correlative electron and X-ray microscopy: probing chemistry and bonding with high spatial resolution." Nanoscale 7, no. 5 (2015): 1534–48. http://dx.doi.org/10.1039/c4nr05922k.

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Benefits and challenges of correlative spectroscopy: electron energy-loss spectroscopy in the scanning transmission electron microscope (STEM-EELS) and X-ray absorption spectroscopy in the scanning transmission X-ray microscope (STXM-XAS).

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Burstein, L., Yoram Shapira, B. R. Bennett, and J. A. del Alamo. "Surface photovoltage spectroscopy of InxAl1−xAs epilayers." Journal of Applied Physics 78, no. 12 (December 15, 1995): 7163–69. http://dx.doi.org/10.1063/1.360425.

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Menushenkov, A. P., A. Yu Ignatov, A. A. Ivanov, D. I. Kochubey, V. A. Chernov, and S. G. Nikitenko. "Polarized XAS spectroscopy of HTSC thin films." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 359, no. 1-2 (May 1995): 236–39. http://dx.doi.org/10.1016/0168-9002(94)01662-3.

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Zhan, Fei, Ye Tao, and Haifeng Zhao. "Alternative difference analysis scheme combiningR-space EXAFS fit with global optimization XANES fit for X-ray transient absorption spectroscopy." Journal of Synchrotron Radiation 24, no. 4 (May 18, 2017): 818–24. http://dx.doi.org/10.1107/s1600577517005719.

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Time-resolved X-ray absorption spectroscopy (TR-XAS), based on the laser-pump/X-ray-probe method, is powerful in capturing the change of the geometrical and electronic structure of the absorbing atom upon excitation. TR-XAS data analysis is generally performed on the laser-on minus laser-off difference spectrum. Here, a new analysis scheme is presented for the TR-XAS difference fitting in both the extended X-ray absorption fine-structure (EXAFS) and the X-ray absorption near-edge structure (XANES) regions.R-space EXAFS difference fitting could quickly provide the main quantitative structure change of the first shell. The XANES fitting part introduces a global non-derivative optimization algorithm and optimizes the local structure change in a flexible way where both the core XAS calculation package and the search method in the fitting shell are changeable. The scheme was applied to the TR-XAS difference analysis of Fe(phen)3spin crossover complex and yielded reliable distance change and excitation population.

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Seredin, P. V. "Structural and Optical Investigations of Heterostructures Based on AlxGa1-xAsyP1-y:Si Solid Solutions Obtained by MOCVD." Physics Research International 2014 (July 23, 2014): 1–11. http://dx.doi.org/10.1155/2014/782357.

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We investigated MOCVD epitaxial heterostructures based on AlxGa1−xAs ternary solid solutions, obtained in the range of compositions x~0.20–0.50 and doped with high concentrations of phosphorus and silicon atoms. Using the methods of high-resolution X-ray diffraction, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy we have shown that grown epitaxial films represent five-component (AlxGa1−xAs1−yPy)1−zSiz solid solutions. The implementation of silicon in solid solution with a concentration of ~ 0.01 at.% leads to the formation of the structure with deep levels, DX centers, the occurrence of which fundamentally affects the energy characteristics of received materials.

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Yimnirun, Rattikorn, Jirapa Tangsritrakul, Saroj Rujirawat, and Sukit Limpijumnong. "Determination of Mn Site in BaTiO₃by X-Ray Absorption Spectroscopy." Advanced Materials Research 55-57 (August 2008): 273–76. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.273.

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In this work, an experimental X-ray Absorption Spectroscopy (XAS) measurement was employed to determine the local structure of Mn in BaTiO3. Synchrotron X-ray absorption near-edge structure (XANES) experiments were performed on Mn-doped BaTiO3 samples. The BaTi0.8Mn0.2O3 powders were used for the XAS experiment. XAS spectra at the Mn K-edge were recorded in transmission mode. The spectra were collected at ambient temperature with a Ge(111) double crystal monochromator and recorded after performing an energy calibration. The features of the measured Mn K-edge XANES were consistent with Mn on the Ti site and inconsistent with Mn on other sites. The clear agreement was the strongest evidence of Mn substituting for Ti in BaTiO3.

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Pascal, Tod A., C. D. Pemmaraju, and David Prendergast. "X-ray spectroscopy as a probe for lithium polysulfide radicals." Physical Chemistry Chemical Physics 17, no. 12 (2015): 7743–53. http://dx.doi.org/10.1039/c4cp05316h.

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Wang, Hongxin, Anthony T. Young, Jinghua Guo, Stephen P. Cramer, Stephan Friedrich, Artur Braun, and Weiwei Gu. "Soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy below 100 eV: probing first-row transition-metalM-edges in chemical complexes." Journal of Synchrotron Radiation 20, no. 4 (May 30, 2013): 614–19. http://dx.doi.org/10.1107/s0909049513003142.

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X-ray absorption and scattering spectroscopies involving the 3dtransition-metalK- andL-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using theM-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution atM-edges.M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information toK- andL-edge spectroscopies. In this study,M2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition,M2,3-edge RIXS on NiO, NiF2and two other covalent complexes have been performed and differentd–dtransition patterns have been observed. Although still preliminary, this work on 3dmetal complexes demonstrates the potential to useM-edge XAS and RIXS on more complicated 3dmetal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed.

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Butorin, Sergei M., Kristina O. Kvashnina, Johan R. Vegelius, Daniel Meyer, and David K. Shuh. "High-resolution X-ray absorption spectroscopy as a probe of crystal-field and covalency effects in actinide compounds." Proceedings of the National Academy of Sciences 113, no. 29 (July 1, 2016): 8093–97. http://dx.doi.org/10.1073/pnas.1601741113.

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Applying the high-energy resolution fluorescence-detection (HERFD) mode of X-ray absorption spectroscopy (XAS), we were able to probe, for the first time to our knowledge, the crystalline electric field (CEF) splittings of the5fshell directly in the HERFD-XAS spectra of actinides. Using ThO2as an example, data measured at the Th 3dedge were interpreted within the framework of the Anderson impurity model. Because the charge-transfer satellites were also resolved in the HERFD-XAS spectra, the analysis of these satellites revealed that ThO2is not an ionic compound as previously believed. The Th6doccupancy in the ground state was estimated to be twice that of the Th5fstates. We demonstrate that HERFD-XAS allows for characterization of the CEF interaction and degree of covalency in the ground state of actinide compounds as it is extensively done for 3dtransition metal systems.

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Joly, L., B. Muller, E. Sternitzky, J. G. Faullumel, A. Boulard, E. Otero, F. Choueikani, et al. "Versatile variable temperature insert at the DEIMOS beamline forin situelectrical transport measurements." Journal of Synchrotron Radiation 23, no. 3 (April 2, 2016): 652–57. http://dx.doi.org/10.1107/s1600577516002551.

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The design and the first experiments are described of a versatile cryogenic insert used for its electrical transport capabilities. The insert is designed for the cryomagnet installed on the DEIMOS beamline at the SOLEIL synchrotron dedicated to magnetic characterizations through X-ray absorption spectroscopy (XAS) measurements. This development was spurred by the multifunctional properties of novel materials such as multiferroics, in which, for example, the magnetic and electrical orders are intertwined and may be probed using XAS. The insert thus enables XAS toin situprobe this interplay. The implementation of redundant wiring and careful shielding also enables studies on operating electronic devices. Measurements on magnetic tunnel junctions illustrate the potential of the equipment toward XAS studies ofin operandoelectronic devices.

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Schoch, Anke, Lukas Burkhardt, Roland Schoch, Kai Stührenberg, and Matthias Bauer. "Hard X-ray spectroscopy: an exhaustive toolbox for mechanistic studies (?)." Faraday Discussions 220 (2019): 113–32. http://dx.doi.org/10.1039/c9fd00070d.

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George, Graham N., Manuel Gnida, Dennis A. Bazylinski, Roger C. Prince, and Ingrid J. Pickering. "X-Ray Absorption Spectroscopy as a Probe of Microbial Sulfur Biochemistry: the Nature of Bacterial Sulfur Globules Revisited." Journal of Bacteriology 190, no. 19 (August 1, 2008): 6376–83. http://dx.doi.org/10.1128/jb.00539-08.

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ABSTRACT The chemical nature of the sulfur in bacterial sulfur globules has been the subject of controversy for a number of years. Sulfur K-edge X-ray absorption spectroscopy (XAS) is a powerful technique for probing the chemical forms of sulfur in situ, but two groups have used it with very different conclusions. The root of the controversy lies with the different detection strategies used by the two groups, which result in very different spectra. This paper seeks to resolve the controversy. We experimentally demonstrate that the use of transmittance detection for sulfur K-edge XAS measurements is highly prone to spectroscopic distortions and that much of the published work on sulfur bacteria is very likely based on distorted data. We also demonstrate that all three detection methods used for X-ray absorption experiments yield essentially identical spectra when the measurements are carried out under conditions where no experimental distortions are expected. Finally, we turn to the original question—the chemical nature of bacterial sulfur. We examine isolated sulfur globules of Allochromatium vinosum and intact cells of a strain of magnetotactic coccus and show that XAS indicates the presence of a chemical form of sulfur resembling S8.

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Deng, Bangjie, Jiawei Yan, Qingmin Zhang, Yaodong Sang, and Haixiao Deng. "Proposal of X-ray absorption spectroscopy and magnetic circular dichroism using broadband free-electron lasers." Journal of Synchrotron Radiation 26, no. 1 (January 1, 2019): 1–10. http://dx.doi.org/10.1107/s1600577518015175.

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X-ray free-electron lasers (XFELs) have been widely used for applications such as X-ray crystallography and magnetic spin probes because of their unprecedented performance. Recently, time-resolved X-ray magnetic circular dichroism (XMCD) with ultrafast XFEL pulses have made it possible to achieve an instantaneous view of atomic de-excitation. However, owing to the narrow bandwidth and coherence of XFELs, X-ray absorption spectroscopy (XAS) and XMCD are time- and effort-consuming for both machine scientists and users of XFELs. In this work, an efficient scheme using a broadband XFEL pulse and single-shot X-ray spectrometer is proposed, in which the XAS and XMCD measurements can be accomplished with the same machine conditions. An evolutionary multi-objective optimization algorithm is used to maximize the XFEL bandwidth offered by the Shanghai Soft X-ray FEL user facility without additional hardware. A numerical example using MnO is demonstrated, showing that, by using approximately 1000 consecutive XFEL shots with a central photon energy of 650 eV and full bandwidth of 4.4%, precise spectral measurements for XAS and XMCD can be achieved. Additional considerations related to single-shot XAS and XMCD are discussed.

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Gandy, Amy S., Martin C. Stennett, and Neil C. Hyatt. "Surface Sensitive Spectroscopy Study of Ion Beam Irradiation Induced Structural Modifications in Borosilicate Glasses." MRS Proceedings 1514 (2013): 75–80. http://dx.doi.org/10.1557/opl.2013.357.

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ABSTRACTFe K edge X-ray absorption (XAS) and Fourier Transform Infra-Red (FT-IR) spectroscopies have been used to study potential structural modifications in sodium borosilicate glasses as a consequence of Kr+ irradiation. Glasses were doped with simulant waste elements and irradiated at room temperature with 450 keV Kr+ ions to a fluence of 2x1015 Kr+ ions cm-1. According to SRIM calculations, a damaged surface region approximately 400nm wide was produced. In order to probe only the damaged surface layer, XAS measurements were taken in total electron yield mode and FT-IR spectroscopy was conducted in reflectance off the glass surface. No change in Fe valence state was detected by XAS following irradiation. Reflectance FT-IR data revealed a shift to higher wavenumbers in the absorption bands located between 850 and 1100 cm-1 in the doped glasses, corresponding to bond stretching in the silicate network. Deconvolution of FT-IR spectra revealed the shift was due to polymerisation of the silicate network. Network connectivity was found to decrease in the un-doped glass, following irradiation. The results suggest an increase in silicate network connectivity by a cation mediated process, and demonstrates the successful application of surface sensitive XAS and FT-IR to the investigation of ion beam induced damage in amorphous materials.

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Yu, Can, Yan Zhang, Ge Lei, Hao Wang, Yu-hang Wang, Bing-Bing Zhang, Da-Rui Sun, et al. "Upgrade of laser pump time-resolved X-ray probes in Beijing synchrotron." Journal of Synchrotron Radiation 26, no. 6 (October 22, 2019): 2075–80. http://dx.doi.org/10.1107/s1600577519012724.

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The upgrade of the laser pump time-resolved X-ray probes, namely time-resolved X-ray absorption spectroscopy (TR-XAS) and X-ray diffraction (TR-XRD), implemented at the Beijing Synchrotron Radiation Facility, is described. The improvements include a superbunch fill, a high-efficiency fluorescence collection, an efficient spatial overlap protocol and a new data-acquisition scheme. After upgrade, the adequate TR-XAS signal is now obtained in a 0.3 mM solution, compared with a 6 mM solution in our previous report. Furthermore, to extend application in photophysics, the TR-XAS probe is applied on SrCoO2.5 thin film. And for the first time, TR-XAS is combined with TR-XRD to simultaneously detect the kinetic trace of structural changes in thin film.

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Bagus, Paul S., Connie J. Nelin, Michel Sassi, Eugene S. Ilton, and Kevin M. Rosso. "Consequences of realistic embedding for the L2,3 edge XAS of α-Fe2O3." Physical Chemistry Chemical Physics 20, no. 6 (2018): 4396–403. http://dx.doi.org/10.1039/c7cp06926j.

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Cluster models of condensed systems are often used to simulate the core-level spectra obtained with X-ray Photoelectron Spectroscopy, XPS, or with X-ray Absorption Spectroscopy, XAS, especially for near edge features.

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Maclennan, Aimee, and Yongfeng Hu. "Investigation of solvation effects on iron(II) and iron(III) salt solutions by X-ray absorption spectroscopy." Canadian Journal of Chemistry 95, no. 11 (November 2017): 1170–77. http://dx.doi.org/10.1139/cjc-2017-0141.

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The effects of solvation on iron salts has been studied by in situ X-ray absorption spectroscopy (XAS). It was seen that the solvated iron is significantly different from the solid precursor when dissolved in a variety of common solvents. Changes in the chemical and electronic properties of the solvated species make it essential to understand what is happening in solution prior to choosing appropriate reference materials for the interpretation of X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) data. An understanding of the complexity of analyzing liquid systems by XAS is gained from this research.

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Giorgetti, Marco. "A Review on the Structural Studies of Batteries and Host Materials by X-Ray Absorption Spectroscopy." ISRN Materials Science 2013 (May 9, 2013): 1–22. http://dx.doi.org/10.1155/2013/938625.

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This review highlights the use of the X-ray absorption spectroscopy (XAS) as a local structural tool for selected atoms in several host materials. The main characteristics of XAS to be element-sensitive and its applicability to all states of matter, including crystalline solids and amorphous and liquid states, permit an in-depth study of the structural properties of a large variety of materials. This includes intercalation materials where a host structure can accommodate guest species. Host guest equilibria are at the basis of a large variety of technological applications; in particular they have been used for energy storage, ion-exchange membranes, electrochromism, and analytical sensing. A selection of XAS experiments conducted in the field of batteries, mainly on cathodes, and applications in the field of metal hexacyanoferrates and double layered hydroxides are outlined.

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Agostini, G., D. Meira, M. Monte, H. Vitoux, A. Iglesias-Juez, M. Fernández-García, O. Mathon, et al. "XAS/DRIFTS/MS spectroscopy for time-resolved operando investigations at high temperature." Journal of Synchrotron Radiation 25, no. 6 (October 23, 2018): 1745–52. http://dx.doi.org/10.1107/s160057751801305x.

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The combination of complementary techniques in the characterization of catalysts under working conditions is a very powerful tool for an accurate and in-depth comprehension of the system investigated. In particular, X-ray absorption spectroscopy (XAS) coupled with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectroscopy (MS) is a powerful combination since XAS characterizes the main elements of the catalytic system (selecting the absorption edge) and DRIFTS monitors surface adsorbates while MS enables product identification and quantification. In the present manuscript, a new reactor cell and an experimental setup optimized to perform time-resolved experiments on heterogeneous catalysts under working conditions are reported. A key feature of this setup is the possibility to work at high temperature and pressure, with a small cell dead volume. To demonstrate these capabilities, performance tests with and without X-rays are performed. The effective temperature at the sample surface, the speed to purge the gas volume inside the cell and catalytic activity have been evaluated to demonstrate the reliability and usefulness of the cell. The setup capability of combining XAS, DRIFTS and MS spectroscopies is demonstrated in a time-resolved experiment, following the reduction of NO by Rh nanoparticles supported on alumina.

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Cotelesage, Julien, Pawel Grochulski, Michel Fodje, James Gorin, Kathryn Janzen, Shaun Labiuk, Graham George, and Ingrid Pickering. "XAS at the Canadian Macromolecular Crystallography Facility." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1525. http://dx.doi.org/10.1107/s2053273314084745.

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Recent additions to the Canadian Macromolecular Crystallography Facility have expanded the capabilities of its bending magnet beamline. It is now possible to perform x-ray absorption spectroscopy (XAS) on crystals. A wide range of biologically relevant metals can be further studied, supplementing diffraction data. XAS can be used to determine if metalloproteins are photoreducing during diffraction data collection. The geometries of metal complexes can also be inferred with near-edge and EXAFS data, often more accurately than crystallography. CMCF-BM can be employed to do the abovementioned techniques on powder and solution samples that contain a metal of interest. One XAS-based technique that shows promise is single crystal plane polarized EXAFS. This technique combines crystallographic data with the findings from XAS to yield a high resolution three dimensional atomic model. More recently a number of the procedural steps required for the acquisition of XAS-based data have been automated in the MxDC software suite. These changes to data collection make it easier for users new to these disciplines to run the XAS-based experiments. By having the necessary equipment to do XAS at a protein crystallography facility, researchers who may not have had the opportunity delve into the field of XAS now can do so with minimal risk in terms of materials, funds and time.

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Dent, A. J., G. Cibin, S. Ramos, A. D. Smith, S. M. Scott, L. Varandas, M. R. Pearson, N. A. Krumpa, C. P. Jones, and P. E. Robbins. "B18: A core XAS spectroscopy beamline for Diamond." Journal of Physics: Conference Series 190 (November 1, 2009): 012039. http://dx.doi.org/10.1088/1742-6596/190/1/012039.

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Dinu, M., D. D. Nolte, and M. R. Melloch. "Electroabsorption spectroscopy of effective-massAlxGa1−xAs/GaAsFibonacci superlattices." Physical Review B 56, no. 4 (July 15, 1997): 1987–95. http://dx.doi.org/10.1103/physrevb.56.1987.

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Cingolani, R., F. Sogawa, Y. Arakawa, R. Rinaldi, M. DeVittorio, A. Passaseo, A. Taurino, M. Catalano, and L. Vasanelli. "Microphotoluminescence spectroscopy of vertically stackedInxGa1−xAs/GaAsquantum wires." Physical Review B 58, no. 4 (July 15, 1998): 1962–66. http://dx.doi.org/10.1103/physrevb.58.1962.

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Buick, Benjamin, Eugen Speiser, Paola Prete, Pasquale Paiano, Nicola Lovergine, and Wolfgang Richter. "Single AlxGa1−xAs nanowires probed by Raman spectroscopy." physica status solidi (b) 247, no. 8 (June 18, 2010): 2027–32. http://dx.doi.org/10.1002/pssb.200983948.

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Nagasaka, Masanari. "Soft X-ray absorption spectroscopy in the low-energy region explored using an argon gas window." Journal of Synchrotron Radiation 27, no. 4 (May 27, 2020): 959–62. http://dx.doi.org/10.1107/s1600577520005883.

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The soft X-ray region below 200 eV is important for investigating chemical and biological phenomena since it covers K-edges of Li and B and L-edges of Si, P, S and Cl. Helium gas is generally used as the soft X-ray transmission window for soft X-ray absorption spectroscopy (XAS) under atmospheric conditions. However, the helium gas window cannot be applied to XAS in the low-energy region since transmitted soft X-rays mostly consist of high-order X-rays due to the low transmission of first-order X-rays. In this study, the argon gas window is proposed as a new soft X-ray transmission window in the low-energy region. High-order X-rays are removed by the absorption of the Ar L-edge (240 eV), and first-order X-rays become the major contribution of transmitted soft X-rays in the low-energy region. Under atmospheric argon conditions, the double-excitation Rydberg series of helium gas (60 eV), Si L-edge XAS of an Si3N4 membrane (100 eV) and S L-edge XAS of dimethyl sulfoxide gas (170 eV) are successfully measured, indicating that the argon gas window is effective for soft X-ray transmission in the low-energy region from 60 eV to 240 eV.

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Klysubun, Wantana, Pinit Kidkhunthod, Pongjakr Tarawarakarn, Panidtha Sombunchoo, Chanapa Kongmark, Sukit Limpijumnong, Saroj Rujirawat, Rattikorn Yimnirun, Gamolwan Tumcharern, and Kajornsak Faungnawakij. "SUT-NANOTEC-SLRI beamline for X-ray absorption spectroscopy." Journal of Synchrotron Radiation 24, no. 3 (April 4, 2017): 707–16. http://dx.doi.org/10.1107/s1600577517004830.

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The SUT-NANOTEC-SLRI beamline was constructed in 2012 as the flagship of the SUT-NANOTEC-SLRI Joint Research Facility for Synchrotron Utilization, co-established by Suranaree University of Technology (SUT), National Nanotechnology Center (NANOTEC) and Synchrotron Light Research Institute (SLRI). It is an intermediate-energy X-ray absorption spectroscopy (XAS) beamline at SLRI. The beamline delivers an unfocused monochromatic X-ray beam of tunable photon energy (1.25–10 keV). The maximum normal incident beam size is 13 mm (width) × 1 mm (height) with a photon flux of 3 × 108to 2 × 1010 photons s−1(100 mA)−1varying across photon energies. Details of the beamline and XAS instrumentation are described. To demonstrate the beamline performance,K-edge XANES spectra of MgO, Al2O3, S8, FeS, FeSO4, Cu, Cu2O and CuO, and EXAFS spectra of Cu and CuO are presented.

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Miyazato, Itsuki, Lauren Takahashi, and Keisuke Takahashi. "Automatic oxidation threshold recognition of XAFS data using supervised machine learning." Molecular Systems Design & Engineering 4, no. 5 (2019): 1014–18. http://dx.doi.org/10.1039/c9me00043g.

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Bagger, Alexander, Ties Haarman, Anna Puig Molina, Poul George Moses, Hirofumi Ishii, Nozomu Hiraoka, Yu-Han Wu, Ku-Ding Tsuei, Ib Chorkendorff, and Frank De Groot. "1s2p resonant inelastic X-ray scattering combined dipole and quadrupole analysis method." Journal of Synchrotron Radiation 24, no. 1 (January 1, 2017): 296–301. http://dx.doi.org/10.1107/s1600577516016933.

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In this study an analysis strategy towards using the resonant inelastic X-ray scattering (RIXS) technique more effectively compared with X-ray absorption spectroscopy (XAS) is presented. In particular, the question of when RIXS brings extra information compared with XAS is addressed. To answer this question the RIXS plane is analysed using two models: (i) an exciton model and (ii) a continuum model. The continuum model describes the dipole pre-edge excitations while the exciton model describes the quadrupole excitations. Applying our approach to the experimental 1s2p RIXS planes of VO2 and TiO2, it is shown that only in the case of quadrupole excitations being present is additional information gained by RIXS compared with XAS. Combining this knowledge with methods to calculate the dipole contribution in XAS measurements gives scientists the opportunity to plan more effective experiments.

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Isomura, Noritake, and Yasuji Kimoto. "Local atomic structure analysis around Mg atom doped in GaN by X-ray absorption spectroscopy and spectrum simulations." Journal of Synchrotron Radiation 28, no. 4 (May 27, 2021): 1114–18. http://dx.doi.org/10.1107/s1600577521004008.

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The identification of the incorporated site of magnesium (Mg) and hydrogen (H) required for p-type formation in gallium nitride (GaN) power devices has been demonstrated by X-ray absorption spectroscopy (XAS). In this study, the fluorescence line of Mg with 3 × 1019 atoms cm−3 was successfully separated from that of Ga using a superconducting tunnel junction array detector with high sensitivity and high energy resolution, and consequently the Mg K-edge XAS spectra of such dilute samples were obtained. The site of Mg atoms incorporated into the GaN lattice was identified as the Ga substitutional site by comparing the experimental XAS spectrum with the simulated spectra calculated by density functional theory. In addition, the presence or absence of H around Mg can be determined through distinctive characteristics expected from the spectrum simulations.

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Cao, Rui, Kolle E. Thomas, Abhik Ghosh, and Ritimukta Sarangi. "X-ray absorption spectroscopy of archetypal chromium porphyrin and corrole derivatives." RSC Advances 10, no. 35 (2020): 20572–78. http://dx.doi.org/10.1039/d0ra02335c.

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Chatterjee, Ruchira, Clemens Weninger, Anton Loukianov, Sheraz Gul, Franklin D. Fuller, Mun Hon Cheah, Thomas Fransson, et al. "XANES and EXAFS of dilute solutions of transition metals at XFELs." Journal of Synchrotron Radiation 26, no. 5 (August 7, 2019): 1716–24. http://dx.doi.org/10.1107/s1600577519007550.

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This work has demonstrated that X-ray absorption spectroscopy (XAS), both Mn XANES and EXAFS, of solutions with millimolar concentrations of metal is possible using the femtosecond X-ray pulses from XFELs. Mn XAS data were collected using two different sample delivery methods, a Rayleigh jet and a drop-on-demand setup, with varying concentrations of Mn. Here, a new method for normalization of XAS spectra based on solvent scattering that is compatible with data collection from a highly variable pulsed source is described. The measured XANES and EXAFS spectra of such dilute solution samples are in good agreement with data collected at synchrotron sources using traditional scanning protocols. The procedures described here will enable XFEL-based XAS on dilute biological samples, especially metalloproteins, with low sample consumption. Details of the experimental setup and data analysis methods used in this XANES and EXAFS study are presented. This method will also benefit XAS performed at high-repetition-rate XFELs such as the European XFEL, LCLS-II and LCLS-II-HE.

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Dávila, M. E., D. Arvanitis, J. Hunter Dunn, N. Mårtensson, P. Srivastava, F. Wilhelm, and K. Baberschke. "In Situ Magnetic-Circular-X-Ray-Dichroism Measurements: An Epitaxial Fe Wedge on Cu(100)." MRS Bulletin 24, no. 1 (January 1999): 41–45. http://dx.doi.org/10.1557/s0883769400051721.

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Circularly polarized x-ray radiation is attracting increasing interest as a tool for the characterization of the electronic, magnetic, and chiral properties of low-dimensional structures. Using circular light (with electric field vector parallel to the orbital plane), a dependence of the measured quantity by changing either the orientation of the light polarization or the magnetization is indicative of the existence of magnetic circular dichroism. It can be observed in x-ray absorption spectroscopy (XAS), in which the photon energy is scanned through an absorption threshold exciting a core electron into an unoccupied valence state using circularly polarized light. Synchrotron radiation sources have made this technique possible. It can also be observed in photo-emission spectroscopy from core and valence levels. Here we focus on magnetic circular x-ray dichroism (MCXD) in XAS as an element-specific tool to investigate magnetic properties of ultrathin films in situ. The application of magneto-optical sum rules enables the determination of the orbital and spin magnetic moments per atom from XAS spectra, as well as the easy magnetization direction.MCXD-based magnetometry in XAS is extensively used by measuring the L absorption edges of 3d-transition metals, where large intensity changes (up to 60%) of the L-edge white lines are observed upon reversal of either the sample magnetization or the light helicity. The high magnetic contrast obtained, combined with the elemental specificity of the technique, allows for the study of very dilute samples such as ultrathin films. We first concentrate on the selection rules governing MCXD in XAS.

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Tierney, George F., Donato Decarolis, Norli Abdullah, Scott M. Rogers, Shusaku Hayama, Martha Briceno de Gutierrez, Alberto Villa, et al. "Extracting structural information of Au colloids at ultra-dilute concentrations: identification of growth during nanoparticle immobilization." Nanoscale Advances 1, no. 7 (2019): 2546–52. http://dx.doi.org/10.1039/c9na00159j.

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Reid, Joel, Toby Bond, Shiliang Wang, Jigang Zhou, and Anguang Hu. "Synchrotron powder diffraction, X-ray absorption and 1H nuclear magnetic resonance data for hypoxanthine, C5H4N4O." Powder Diffraction 30, no. 3 (August 13, 2015): 278–85. http://dx.doi.org/10.1017/s0885715615000457.

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Synchrotron powder X-ray diffraction, X-ray absorption spectroscopy (XAS), and proton nuclear magnetic resonance (1H-NMR) data have been used to examine the structure of hypoxanthine, 1,7-dihydro-6H-purin-6-one (C5H4N4O), a purine base that participates in numerous metabolic processes. XAS and 1H-NMR spectroscopy were used to determine that hypoxanthine was present in its keto form (both in solid state and dissolved in an organic solvent). Rigid body refinement was performed with the Rietveld software package GSAS yielding triclinic lattice parameters of a = 7.1179 (2) Å, b = 9.7830 (3) Å, c = 10.4009 (3) Å, α = 58.876 (1)°, β = 67.609 (1)°, and γ = 71.937 (2)° (C5H4N4O, Z = 4, space group P$\bar 1$).

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LERCH, P., E. G. MORONI, and T. JARLBORG. "EFFECTS DUE TO THE NEAR MAGNETIC TRANSITIONS IN ZrV2." International Journal of Modern Physics B 07, no. 01n03 (January 1993): 774–77. http://dx.doi.org/10.1142/s0217979293001633.

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Local spin density calculations for the large enhanced paramagnet ZrV2 in the C15 structure have been performed. The ground-state is paramagnetic but almost degenerate with the ferromagnetic state. Here we study different ways to trigger ferromagnetism. First we study the possibility of having thermal excitations between non-magnetic and magnetic states, in which case a anti invar effect would be possible. Secondly, in calculations with V core holes which are models of X-ray absorption spectroscopy (XAS) we study the possibility of having induced magnetism via core polarization. Calculations of complete XAS spectra including matrix elements suggest that these nearly magnetic systems are good candidates for giving quite unusual results in spectroscopy measurements.

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Poswal, Ashwini Kumar, Ankur Agrawal, Himanshu Kumar Poswal, Dibyendu Bhattacharyya, Shambhu Nath Jha, and Naba Kishore Sahoo. "Augmentation of the step-by-step Energy-Scanning EXAFS beamline BL-09 to continuous-scan EXAFS mode at INDUS-2 SRS." Journal of Synchrotron Radiation 23, no. 6 (October 7, 2016): 1518–25. http://dx.doi.org/10.1107/s160057751601362x.

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An innovative scheme to carry out continuous-scan X-ray absorption spectroscopy (XAS) measurements similar to quick-EXAFS mode at the Energy-Scanning EXAFS beamline BL-09 at INDUS-2 synchrotron source (Indore, India), which is generally operated in step-by-step scanning mode, is presented. The continuous XAS mode has been implemented by adopting a continuous-scan scheme of the double-crystal monochromator and on-the-fly measurement of incident and transmitted intensities. This enabled a high signal-to-noise ratio to be maintained and the acquisition time was reduced to a few seconds from tens of minutes or hours. The quality of the spectra (signal-to-noise level, resolution and energy calibration) was checked by measuring and analysing XAS spectra of standard metal foils. To demonstrate the energy range covered in a single scan, a continuous-mode XAS spectrum of copper nickel alloy covering both Cu and NiK-edges was recorded. The implementation of continuous-scan XAS mode at BL-09 would expand the use of this beamline inin situtime-resolved XAS studies of various important systems of current technological importance. The feasibility of employing this mode of measurement for time-resolved probing of reaction kinetics has been demonstrated byin situXAS measurement on the growth of Ag nanoparticles from a solution phase.

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Müller, Rafael J., Jinggang Lan, Karla Lienau, René Moré, C. A. Triana, Marcella Iannuzzi, and Greta R. Patzke. "Monitoring surface transformations of metal carbodiimide water oxidation catalysts by operando XAS and Raman spectroscopy." Dalton Transactions 47, no. 31 (2018): 10759–66. http://dx.doi.org/10.1039/c8dt01587b.

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Chemical and structural transformations at the electrode surface of metal carbodiimides MNCN (M = Co, Ni, Mn, Cu), were studied by operando Raman and XAS spectroscopy during electrocatalytic water oxidation

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Journal articles on the topic 'XAS spectroscopy'

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